#gridPanel{
  width:480px; height:480px;
  margin:0 auto; position:relative;
  background:#bbada0; border-radius:10px;
}
.cell{
  width:100px; height:100px; border-radius:6px;
  background:#ccc0b3; position:absolute;
  font-size:60px; text-align:center; color:#fff;
  line-height:100px;
}
[id^="c0"]{top:16px;}
[id^="c1"]{top:132px;}
[id^="c2"]{top:248px;}
[id^="c3"]{top:364px;}
[id$="0"]{left:16px;}
[id$="1"]{left:132px;}
[id$="2"]{left:248px;}
[id$="3"]{left:364px;}

.n2{background-color:#eee3da}
.n4{background-color:#ede0c8}
.n8{background-color:#f2b179}
.n16{background-color:#f59563}
.n32{background-color:#f67c5f}
.n64{background-color:#f65e3b}
.n128{background-color:#edcf72}
.n256{background-color:#edcc61}
.n512{background-color:#9c0}
.n1024{background-color:#33b5e5}
.n2048{background-color:#09c}
.n4096{background-color:#a6c}
.n8192{background-color:#93c}
.n2,.n4{color:#776e65}
.n1024,.n2048,.n4096,.n8192{font-size:40px}

p{
  width:480px; margin:0 auto;
  font-size:40px; font-family:Arial;
  font-weight:bold; padding-top:15px;
}
#gameOver{ display:none;
  position:absolute; 
  top:0; left:0; right:0; bottom:0;
  background:rgba(55,55,55,.5);
}
#gameOver>p{
  width:300px; height:200px;
  position:absolute; top:50%; left:50%;
  margin-left:-150px; margin-top:-100px;
  background:#fff; 
  
  text-align:center; line-height:1.5em;
  border-radius:10px; border:1px solid #edcf72;
}
#gameOver .btn{
  padding:10px;
  color:#fff;
  background:#9f8d77;
  border-radius:6px;
  text-decoration:none;
}